We based ourselves on the observed HMXBs in the Milky Way that we compiled in a previous work [1]}. To summarize, the HMXBs were retrieved from [2]}, a catalogue dedicated to HMXBs, and completed by more recent discoveries from the fourth catalogue of INTEGRAL sources [3]}. As a significant number of those sources were still at the stage of candidate HMXBs, we manually checked every catalogued HMXBs to ensure that they have no ambiguity in their identification (high energy to optical–infrared counterparts and early spectral type of the companion). The systems with a confirmed HMXB status were queried in Gaia EDR3 and, when possible, associated to a single Gaia counterpart.
